Human interaction with touch-enabled devices is generally constrained to the surface of these devices through touch sensors. However, the size range of computing devices, ranging from tiny wearable devices (e.g., smart watches) to huge displays, can limit the touch sensor as the primary input medium. In the case of small screens, touching the screen can be inherently problematic as human fingers can cover a portion of the screen, obstructing visibility of the display. On the other hand, interacting with touch sensors on large displays can be cumbersome. In some cases, it may be advantageous to be able to detect a user gesture without relying on touch sensors.